West versus East Antarctica

The Antarctic continent is made up of two distinct geographic regions, separated by one of the largest mountain ranges on Earth, the Transantarctic Mountains (TAM). This impressive mountain chain cuts across Antarctica, being over 3500 km in length, 100-200 km wide and reaching heights of 4500 m. By aligning a map of Antarctica so the Greenwich Meridian (zero longitude) is at the top, these very different regions on either side of the TAM, can be compared.

West Antarctica forms the hook to the left, East Antarctica forms the rest of the continent.

Practical Task Introduction Convection is the movement of a liquid or gas, due to West Antarctica East Antarctica differences in it's density. Temperature differences cause density differences. • much younger • extremely ancient geological history geologically history What to do 1. Stir a teaspoon of Miso • rocks are mainly less • oldest known Antarctic soup paste into a glass than 500 million years rocks at 4000 million or cup of hot water old. years old 2. Allow to stand and • a large part is below sea • mainly above sea level watch for convection level currents. • composed of islands, • composed of a large archipelagos and small mass of ancient rock How it works land masses Within the glass the movement is caused by the hotter • connected by the West • covered by the thick parts of the Miso soup being less dense and rising, Antarctic Ice Sheet East Antarctic ice sheet likewise the colder liquid tends to sink. Since heat is lost (WAIS) (EAIS) from the outer surfaces a central column of rising soup is formed. Even small temperature differences are sufficient • WAIS sits on land that is • EAIS flows outwards to keep this process occurring. mostly below sea level over ancient bedrock Note that it is not the actual temperature of the soup which drives the convection current but rather differences • mountainous and • mainly flat except for the in soup temperature, which explains why the current spectacular throughout buried Gamburtsev continues as the soup cools. Mountains Convection currents like this occur in all hot liquids (and gases) but are made more visible here because of the soy paste within the soup. The Transantarctic Mountains The uplift of the Transantarctic Mountains was caused Relevance by the same process which split Gondwana apart. After • Convection currents in the Earths mantle contribute to Gondwana disintegrated, Antarctica continued to be the movement of continents (e.g.Antarctica). stretched (rifted) and pulled apart. This stretching caused • Convection currents in the ocean caused by East and west Antarctica to drift apart and the differences in water temperature (and salinity) drive Transantarctic Mountains to be uplifted on the edge of the ocean currents. These currents control Earths food rift. chains, weather and climate. As the surface stretched some crustal blocks sank, creating large scale features which remain to this day, namely: • the steep eastern faces of the Transantarctic Adapted from material by Bryan Storey, University of Mountains. Canterbury by Donald Reid, iMatters.co.nz in association • the large areas of West Antarctic that lie below sea with Gateway Antarctica, University of Canterbury. level. Curricula: Science L4 - 8, Social Studies L3 - 4, Geography L6 - 8. Images: Donald Reid, Alexrk2, Wikicommons

For a full range of Antarctic and Southern Ocean resources visit: The Antarctic Hub www.antarctichub.org